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Lactic Acid From Alfalfa

Lactic acida colorless or slightly yellow, syrupy liquidis
naturally formed by the fermentation of lactose, or milk sugar. Its name comes
from the Latin word "lac," which means milk. Commercially, lactic
acid can be made synthetically from chemicals or organically as a byproduct of
corn fermentation.

Last year, ARS agricultural engineer
Richard G. Koegel in Madison, Wisconsin, and University of Wisconsin
researchers were the first scientists to make lactic acid from alfalfa. This
accomplishment will give alfalfa an extra economic boost.

The USDA-Wisconsin research partnership has already produced several
alfalfa-derived products, such as carotenoids and protein concentrates, worth
from $1,000 to $2,000 per acre annually.

Lactic acid is commonly used as a food additive for flavor and preservation,
but a new market for organic lactic acid exists for making biodegradable
plastics. The current lactic acid market in the United States is about 50,000
tons per year, more than half of which is imported.

The alfalfa fibrous fraction, from which lactic acid is made, results when
juice is expressed from freshly cut herbage to make other high-value products,
including food- and feed-grade proteins and carotenoids.

ARS research with transgenic alfalfa also produced industrially valuable
enzymes.

Instead of using chemical treatments, Koegel pretreated alfalfa fiber for 2
minutes in hot water at 430oF and 350 pounds-per-square-inch
pressure. With hot-water pretreatment, hydrolytic enzymes, and a
Lactobacillus bacterium, the researchers got lactic acid
yields as high as 60 percent.

"Many microorganisms can ferment either five- or six-carbon sugars. The
Lactobacillus bacterium that we used is an exception because it can
ferment both," Koegel says.

Koegel is now attempting to boost lactic acid yields using the microbe
without pretreatment. If this work proves successful, it may help lower
industry's cost of production.

Growing alfalfa in some agricultural areas is preferred over corn and
soybeans, which require more fertilizer and soil tillage that can lead to soil
erosion. Another benefit: Alternating alfalfa with corn and soybeans reduces
pesticide use and increases yield of corn and beans.By
Linda Cooke McGraw,
Agricultural Research Service Information Staff.